后退不能从片段到片段工作。（我的应用程序包含导航抽屉和标签视图。）我的主要活动代码如下。我已经添加了背压方法，请帮助我....
public class Main Activity extends Activity {
ImageView image;
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
// nav drawer title
private CharSequence mDrawerTitle;
// used to store app title
private CharSequence mTitle;
// slide menu items
private String[] navMenuTitles;
private TypedArray navMenuIcons;
private ArrayList<NavDrawerItem> navDrawerItems;
private NavDrawerListAdapter adapter;
ExpandableListView expListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Runtime.getRuntime().maxMemory();
// load slide menu items
navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
// nav drawer icons from resources
navMenuIcons = getResources()
.obtainTypedArray(R.array.nav_drawer_icons);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.list_slidermenu);
navDrawerItems = new ArrayList<NavDrawerItem>();
// Home
navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
// Find People
navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
// Photos
navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
// Communities, Will add a counter here
navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1)));
// Pages
navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
// What's hot, We will add a counter here
navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[6],
// Recycle the typed array
navMenuIcons.recycle();
mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
// mDrawerLayout.setBackgroundDrawable(new ColorDrawable(R.drawable.border));
// setting the nav drawer list adapter
adapter = new NavDrawerListAdapter(getApplicationContext(),
navDrawerItems);
mDrawerList.setAdapter(adapter);
ActionBar actionBar = getActionBar();
// enabling action bar app icon and behaving it as toggle button
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
actionBar.setHomeButtonEnabled(true);
actionBar.setBackgroundDrawable(new ColorDrawable(Color.WHITE));
actionBar.setCustomView(R.layout.custom_view);
// actionBar.setCustomView(R.layout.custom_view1);
actionBar.setDisplayShowCustomEnabled(true);
actionBar.show();
addListenerOnButton();
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.draw,//nav menu toggle icon
R.string.app_name, // nav drawer open - description for accessibility
R.string.app_name // nav drawer close - description for accessibility
) {
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
// calling onPrepareOptionsMenu() to show action bar icons
invalidateOptionsMenu();
}
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle(mDrawerTitle);
// calling onPrepareOptionsMenu() to hide action bar icons
invalidateOptionsMenu();
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
if (savedInstanceState == null) {
// on first time display view for first nav item
displayView(0);
}
}
/**
* Slide menu item click listener
* */
private class SlideMenuClickListener implements
ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// display view for selected nav drawer item
displayView(position);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// toggle nav drawer on selecting action bar app icon/title
if (mDrawerToggle.onOptionsItemSelected(item)) {
}
return true;
}
/**
* Diplaying fragment view for selected nav drawer list item
* */
private void displayView(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 0:
fragment = new FirstFragment();
break;
case 1:
fragment = new HomeFragment();
break;
case 2:
fragment = new FindPeopleFragment();
break;
case 3:
fragment = new PhotosFragment();
break;
case 4:
fragment = new PagesFragment();
break;
case 5:
fragment = new CommunityFragment();
break;
default:
break;
}
**Edited Code:**
if (fragment != null) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.addToBackStack(null);
ft.replace(R.id.frame_container, fragment);
// Add this transaction to the back stack, so when the user presses back,// it rollbacks.
ft.commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(navMenuTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
private void addListenerOnButton() {
// TODO Auto-generated method stub
image = (ImageView) findViewById(R.id.actionBarLogo);
image.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Fragment fd2 = new MovieActivity();
android.app.FragmentTransaction ft2 =
getFragmentManager().beginTransaction();
ft2.replace(R.id.frame_container, fd2);
ft2.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft2.addToBackStack(null);
ft2.commit();
}
});
}
@Override
public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
}
else {
getFragmentManager().popBackStack();
}
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
}
答案 0 :(得分：1)
在处理所有片段的activity内，使用
@Override
public void onBackPressed() {
int count = getSupportFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
}
else {
getSupportFragmentManager().popBackStack();
}
}
当片段backstack条目计数为0时，表示所有片段都从backstack中弹出。所以你只需执行super.onBackPressed()即可。但是当堆栈不为空时，当您按下后退按钮时，您需要从后台堆栈中弹出最顶层的片段，以便进行正确的反向导航。
注意：如果要导入getFragmentManager().getBackStackEntryCount()，请使用getSupportFragmentManager().getBackStackEntryCount()代替android.app.Fragment。
修改
既然您已经更改了onBackPressed()代码，接下来要做的就是在代码中更改此代码。
if (fragment != null) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.frame_container, fragment);
// Add this transaction to the back stack, so when the user presses back,// it rollbacks.
ft.addToBackStack("Give a Tag for the fragment here");
ft.commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(navMenuTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
基本上我们在这里做的是将一个特定的片段添加到片段backstack中，同时替换它以便在执行onBackPressed()活动时count变量将存储片段backstack中存在的片段数量，然后进行适当的后退导航。